I used to sell and install air tag axles on grain trucks built by a company in IA called Silent Drive, 712-737-4865.The part that would be of interest to you was a 12V-DC compressor in a steel frame mounted box that proved very successful. Over a period of several years I never had to repair or replace one. It would be perfect for your application. A standard trailer air reservoir is what I used and would mount it on the front crossmember.It was the best setup I ever found for adding an air suspension to a hydraulic brake truck. You may want to give them a call and see if they still offer it.
